Alloy materials are used for various applications including structural members constituting skeletons of construct structures or instruments, various mechanism members, and the like, and in many cases, are also used for application in severe environments in which steel materials or aluminum materials are difficult to use. For example, nickel-based alloys, cobalt-based alloys, and the like have been developed which are applied to turbine members or the like provided in airplanes or power generators and are also applicable to hyperpyrexia environments of 1000° C. or higher. In addition, high alloy steel and the like have also been developed which can exhibit high corrosion resistance and high wear resistance even under such hyperpyrexia environments.
In recent years, as a type of alloy materials, multi-element alloys called high-entropy alloys (HEAs) have been drawn attention. The high-entropy alloys are generally regarded as alloys that are composed of approximately five or more elements and contain each element at an equiatomic ratio or an atomic ratio near the equiatomic ratio. The high-entropy alloys have characteristics in that the atomic diffusion rate is slow and are excellent in heat resistance, high-temperature strength, corrosion resistance, and the like. Thus, the high-entropy alloys are expected to be applied to uses in severe environments.
As a technique to which a high-entropy alloy is applied, for example, PTL 1 discloses a method for manufacturing an ultra-hard composite material, the method including a step of mixing at least one ceramic phase powder and a multi-element high-entropy alloy powder to form a mixture, a step of green compacting the mixture, and a step of sintering the mixture to form an ultra-hard composite material, in which the multi-element high-entropy alloy powder consists of 5 to 11 main elements, with each main element occupying 5 to 35 mol % of the multi-element high-entropy alloy powder.
Further, NPL 1 discloses that the size effects on the microstructure and mechanical properties of a high-entropy alloy containing Al, Co, Cr, Fe, and Ni at an equiatomic ratio are analyzed.